Ignition systems for internal combustion engines



Oct. 16, 1962; s. BARKER 3,059,148

" 'IGNITION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed July 19, 1960 L INVENTOR d'fazz// 54117592" A'ITORN EY tates This invention relates to ignition systems for internal combustion engines for automotive service, and more particularly to such a system with which longer life of the ignition points and spark plugs will be available, together with improved and smoother operation of the engine.

In the operation of conventional ignition systems the heavy current flowing through the primary winding builds up the magnetic flux of the iron core to a saturation point, then when the ignition points are opened by the action of the timing cam, the flow of current through the primary winding is interrupted so that a rapid breakdown of the magnetic field of the iron core produces a current in the primary winding of the coil which flows :to the condenser across the open points, charging the condenser to a voltage equal to its capacitance. This produces a high in the coil primary and secondary windings thereby making a very high voltage available for the spark plug.

While this high voltage is produced, radio frequency oscillations are also produced and while it is not entirely certain it is believed that the current flow attendant on these oscillations is at least in part responsible for the pitting of the points by an electro-deposition action.

It is the principal object of the present invention to suppress the flow in automotive ignition systems of radio frequency oscillations.

It is a further object of the present invention to provide an ignition system for automotive vehicles with which greatly prolonged life of the ignition points is obtained.

It is a further object of the present invention to provide an ignition system for automotive vehicles with which the normal life of the spark plug electrodes is greatly extended.

It is a further object of the present invention to provide an ignition system for automotive vehicles with which a suppressor eifect of high frequency oscillations is obtained in a manner which does not introduce any tendency to difficult starting of the engine.

It is a further object of the present invention to provide an ignition system in which the open point time can be reduced thereby permitting more rapid operation of the ignition system.

It is a further object of the present invention to provide an ignition system for automotive vehicles with which smoother operation of the engine will be obtained.

Other objects and advantageous features of the invention will be apparent from the specification and claims.

The nature and characteristic features of the invention will be more readily understood from the following description, taken in connection with the accompanying drawings forming part hereof, in which:

FIGURE 1 is a diagrammatic view of a conventional form of ignition system in common use;

FIG. 2 is an oscilloscope trace pattern as obtained from the ignition system illustrated in FIG. 1;

FIG. 3 is a diagrammatic view of a preferred form of ignition system in accordance with the present invention;

FIG. 4 is a view similar to FIG. 3, showing another preferred form of ignition system in accordance with the present invention; and

FIG. 5 is an oscilloscope trace pattern as obtained with the ignition systems illustrated in FIGS. 3 and 4.

It should, of course, be understood that the description and drawings herein are illustrative merely, and that atent ice various modifications and changes may be made in the structure disclosed without departing from the spirit of the invention.

Referring now more particularly to FIG. 1 of the drawings, the ignition system there shown preferably includes conductors 10 and 11, connected to any suitable source of energy (not shown), such as a conventional generator or storage battery. One of the conductors, such as the condutor 10, is preferably connected to one terminal of the primary winding 12 of an ignition coil 13 having an iron core 14. The other terminal of the primary winding 12 is connected by a conductor 15 to one terminal of the secondary winding 16 of the ignition coil 13.

The terminal of the primary coil 12 to which the conductor 15 is connected is also connected by a conductor 17 to a breaker arm 18 operated by a cam 19 for controlling the make and break of the ignition points 20 and 21. The fixed point 21 is connected by a conductor 22 to ground and to the conductor 11 and a condenser 23 is shunted across the points 20 and 21.

The other terminal of the secondary winding 16 is connected to a distributor 25 having a plurality of conductors 26 each leading therefrom to one of the spark plugs 27 which in turn are grounded to the engine.

Referring now more particularly to FIG. 2 of the drawings, an oscilloscope trace pattern is there illustrated of a character obtained with the ignition system of FIG. 1.

Upon reference to that pattern in which the events occurring in the system are shown the opening of the points is illustrated at a, with the spark at one of the plugs from a to b, the condenser function time of the condenser 23 from a to c, the open point time of the breaker points 2% and 21, from a to 2, with the breaker points closing from d to e. The cam angle at which the points are closed is represented by the interval from e to a. The residual voltage effect after spark discharge is in the interval from b to c.

It will be noted that during the interval a to b of the spark discharge a number of tracings present indicate radio frequency oscillations occurring with the spark.

Referring now more particularly to FIG. 3 of the drawings, the ignition system there illustrated is essentially the same as that illustrated in FIG. 1, but with a blocker or suppressor 3i shunted across the primary winding 12 of the ignition coil 13. This blocker or suppresor 30 preferably consists of a multiple plate rectifier of the metallic type. Such rectifier is not a pure rectifier, but has internal resistance which prevents leakback. Rectifiers of this type are currently available.

Referring now to FIG. 4 of the drawings, in which another preferred form of ignition system is illustrated, the blocker or suppressor 30 there shown is the same as that referred to in connection with FIG. 3, but is shown as shunted across the breaker points 20 and 21.

When the suppressor or blocker 30 is employed as shown in FIGS. 3 and 4, the oscilloscope trace pattern as illustrated in FIG. 5 is obtained. It will be noted upon comparison with FIG. 2 that the plug spark between a and b seems to be a different shape with a tendency to rise, and with an absence of the multiple tracings which appear between a and b on FIG. 2. The spark discharge from a to b is followed by a more rapid reduction from b to c of the residual voltage.

It will be noted that because of the short suppression time of the residual voltage, the open point time of the ignition points can be reduced thus permitting more frequent firing than has heretofore been possible.

The clean spark obtained as shown between a and b is believed to contribute to the extension of the effective life of the ignition points 20 and 21 and extension of the effective life of the spark plugs 27.

Smoother operation of the engine has'also been noted in use.

I claim: p 7 r In an ignition system for internal combustion engines, an induction coil having a primary circuit including a primary winding and a secondary circuit, a distributor connected to the secondary circuit of the coil, a spark plug' to which said distributor is connected, a source of direct current electrical energy, connections from the terminals of the primary circuit to said source, one of said 10 connections having an interrupter interposed therein, a condenser connected across said interrupter, and means 5 connected to the positive terminal of the source.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,149 Leonard Apr. 18, 1933 2,382,808 Ochsenbein Aug. 14, 1945 3,007,082 Kappele Oct. 31, 1961 

